Biology - Page 3

Researchers from the University of Florida and Hunan Univeristy developed DNA-directed silver nanoparticles (Ag NPs) grown on graphene oxide (GO). These so called Ag@dsDNA@GO composites act as antibacterial agents, decreasing X. perforans (a model plant pathogenic bacterium) cell viability in culture and on plants.

The researchers say that this material exhibit good antibacterial activity due to the synergistic effect between the silver nanoparticles (AgNPs) and the graphene oxide (GO). In a greenhouse experiment they applied this material on tomato transplants and they reported significant reduction of disease caused by bacterial spot compared to the untreated control and the control treated with copper + mancozeb (a standard treatment). The material did not induce any phytotoxic effect on the leaves.

Researchers from the US Naval Research Laboratory (NRL) have moved liquid droplets using long chemical gradients formed on graphene. The idea is that by changing the concentration of either fluorine or oxygen (formed using a simple plasma-based process) you can either push or pull droplets of water (also nerve agent simulant) across the surface of the graphene.

The researchers say that this could lead to applications relating to biological or chemical sensors, and also perhaps electronics and mechanical resonators. They say that in the future, such chemical gradients could be used to perhaps move single molecules.

Researchers from Stanford developed a new way to produce graphene ribbons using DNA strands. GNRs have a bandgap and so can be used as building blocks for transistors, and indeed the researchers produced transistors based on GNRs produced using this new process.

The process goes like this: it starts with a silicon substrate, dipped in a DNA solution (derived from bacteria). They then combed the DNA strands into relatively straight lines (using a common technique). They exposed the DNA to a copper salt solution which allowed the copper ions to be absorbed into the DNA.

Researchers from the Naval Research Laboratory at George Mason University report that graphene can replace Carbon Nanotubes (CNTs) in glucose sensors. The researchers use multilayered graphene petal nanosheets enhanced with platinum nanoparticles and enzyme glucose oxidase to monitor glucose concentrations found in saliva, tears, blood, and urine.

In past research, the researchers used CNTs with platinum nanoparticles to provide sensitive sensors. But these sensors were not stable as spacing of the nanoparticles on the CNTs significantly impacted the biosensor performance (as glucose diffusion is blocked when nanoparticles are too closely packed). In addition, they suffered from diffusion restrictions from neighboring nanoparticles.

Grafoid and ProScan Rx Pharma announced a new joint-venture partnership to develop MesoGraf graphene-based nanotechnology platform for the precise targeting and thermal eradication of solid cancer tumors. This new platform aims to overcome the side effects and strong limitations of common cancer therapies.

The two companies established a new company called Calevia. Grafoid invested in Calevia and will co-manage the company. The new company will first target prostate cancer using ProScan’s anti-PSMA antibody. The new company will use a partially edge-functionalized MesoGraf derivative called MesoGraf Xide. This nanomaterial instantly transforms near infrared (NIR) light into heat.

Researchers from the University of Minnesota are developing a sensor platform that will help create an artificial pancreas. The wireless sensor that will continually monitor blood glucose will be based on graphene and it can be placed in blood vessels for accurate and continual monitoring.

This new project was funded by the 2013 Discovery Transformation Grant Program. This is one of four projects that received $2 million in total.

Researchers from the University of Science and Technology of China (USTC) discovered that protein-coated graphene oxide can be used to create efficient anti-bacteria agents. The GO sheets were used as a template to guide silver (or Au@Ag core-shell particles, to be exact) into a 2D array. In this configuration, the silver is much more efficient that with with individual nanoparticles and silver ions.

Mechanical studies showed strong adhesion of the 2D Au@Ag nano-assembly on the cell surface, which cause an aggregation and cellular lysis of the bacteria. The increased local concentration of silver around the bacteria and the "polyvalent" nanoparticle-bacterium interaction were both critical.

New research demonstrated that graphene can kill bacteria by slicing through their membranes and pulling out their phospholipids. Graphene may be used in the future as an antimicrobial material for everyday use, applied directly to wounds. A sort of graphene "band-aid". Graphene may also be used to create novel antibiotics.

The researcher explained that graphene cut through the membranes and extracted large amounts of phospholipids from cell membranes because of strong dispersion interactions between graphene and lipid molecules. Both the graphene and and phospholipids are pushed together by water, which creates hydrophobic interactions.

Researchers from the University of California, Berkeley created a light-responsive hydrogel made from graphene and elastin-like proteins. When light (a laser) is shining on the gel, it curls inward rapidly. This property is called phototropism - plants use it to orient towards a light source. This material may be useful in robots, drug delivery and synthetic tissue engineering.

The idea behind the new material is that the graphene sheet generates heat when exposed to infrared light,. This causes the proteins to release the water the cling to when not heated.

Researchers from the Irish nanoscience institute CRANN developed a new graphene-based sensor technology that could become a new platform for low-energy, remotely powered sensors for all sorts of applications. One such application, specifically mentioned by the researchers is air quality control systems in automobiles. Other applications may include bacteria and parasite detection and diseases diagnosis.

The researchers developed what they refer to as Chemically Modulated Graphene Diodes (or GDS). These are made from a single layer of graphene on silicon. The graphene is exposed to liquids or gases and the diode can be made (by different doping) so that various absorbates will transfer charge.